PROJECT SUMMARY The annual incidence of pediatric heart failure due to congenital heart disease (CHD) is 1 to 2 cases per 1000 births. Whereas 10,000 to 14,000 children are hospitalized annually in the United States waiting for a new heart, only 444 transplants were performed in 2016, illustrating the drastic shortage of donor hearts. The only long- term treatment alternative to a heart transplant is the implantation of a ventricular assist device (VAD), a pump that helps the failing heart to pump blood until a new heart is available. However, these VADs are too large to be fully implantable in children under 4 years of age; therefore, these VADs are placed externally near the abdomen, with tubes running through the skin. These tubes can lead to infection, and they prevent the children from leaving the hospital for the duration of pump support, which can exceed 1 year. Additionally, the survival rate of patients weighing less than 5 kg with the currently available VADs is dismal; more than 60% of these children die after VAD implantation, stroke being the most common cause of death. Therefore, there is a need to design a safer, fully implantable pediatric VAD to improve the survival of both infants and young children. This VAD also needs to be adjustable with the child?s growth and development, meaning that it must provide higher blood flow and pressure as the child grows. The objective of this study is to develop the first fully implantable VAD (NeoVAD) for infants and young children, which would help the failing heart until a suitable donor heart is available. In Aim 1, development of a miniature magnetic levitation system to eliminate mechanical wear and optimize the pump performance is proposed, which will provide a long-term circulatory support. The hemodynamic performance of the NeoVAD in steady-state flow environments at different physiological operating points will be investigated in Aim 2. Finally, in Aim 3, systemic hemocompatibility and hemodynamic performance of the NeoVAD will be evaluated by in vitro and large-animal studies. This pump, after implantation, would allow pediatric heart failure patients to return to a near-normal life outside the hospital. This research will give new insights into designing a pump that can support the failing heart for a wide range of patients, from infants to children weighing up to 20 kg. This wide range of support would eliminate the need to change VADs or undergo multiple heart transplants as the child grows, both of which are risky procedures. Also, this research will include an in-depth study of pump-blood interaction across the patient age range, allowing us to study how blood shear stress is affected by changes in blood flow rate and pressure as the child grows. This study will enable us to design the first safe, fully implantable VAD for young children, which would reduce the risk of stroke, bleeding, and infection and improve their chances of survival. We expect that with the implanted NeoVAD, pediatric CHD patients can live a near-normal life outside the hospital, which would be a significant improvement in their quality of life.